[storm] Announcing Storm 0.17!

[Jamu Kakar]

The Storm team is proud to announce Storm 0.17!

The new release includes a number of new features:

 * Optimized any and is_empty ResultSet methods
 * String-based order by on ReferenceSet
 * Improved safety checks to help prevent bugs and aid debugging
 * Get a Select expression for a ResultSet
 * SQLite reserved words are correctly handled

This release includes official packages for all supported releases
of Ubuntu.  They are available in the Storm team's PPA:

 https://edge.launchpad.net/~storm/+archive/ppa

You can find the release files at:

 https://launchpad.net/storm/+download

You can always get the latest source code from Launchpad:

 bzr branch lp:storm

Finally, you can join us in the #storm channel on irc.freenode.net
and on the Storm mailing list:

 https://lists.canonical.com/mailman/listinfo/storm

Read on for more...


Optimized any and is_empty ResultSet methods
--------------------------------------------

The ResultSet.any, ResultSet.is_empty and the equivalents on
ReferenceSet strip ORDER BY clauses before running queries.  This
will provide a performance boost for queries that would match a
large number of rows.


String-based order by on ReferenceSet
-------------------------------------

When the Storm metaclass is used as the base for Storm model
classes, strings can be used to define ReferenceSets, for example:

  class Library(Storm):

      books = ReferenceSet(library_id, "Book.library_id")

This makes it easy to workaround circular import issues.  The
default ORDER BY clause can now be defined using a string:

  class Library(Storm):

      books = ReferenceSet(library_id, "Book.library_id",
                           order_by="Book.title")


Improved safety checks to help prevent bugs and aid debugging
-------------------------------------------------------------

Store and Connection objects have new block_access and
unblock_access methods, designed to prevent access to the database
during unexpected times, such as between web requests.  If an
attempt to access the database is made while a connection is blocked
a ConnectionBlockedError will be raised.  Finally, if a
ZStorm-managed store is accessed in a different thread from the one
in which it was created a ZStormError will be raised.


Get a Select expression for a ResultSet
---------------------------------------

ResultSet has a new get_select_expr that can be used to get a Select
expression, useful when building a subselect, configured with the
same settings as the ResultSet.  A list of columns must be provided:

  result = store.find(Book, Library.id.is_in([1,2,3]))
  select = result.get_select_expr(Book.title, Book.author)


SQLite reserved words are correctly handled
-------------------------------------------

In addition to the standard SQL92 reserved words, SQLite has it's
own set reserved words.  Storm is now aware of them and will perform
escaping correctly, making it easier for users that have table and
column names that conflict with this list.


Detailed changelog
------------------

Improvements:

 - The order_by parameter defined on ReferenceSet can now be
   specified as a string, to workaround circular dependency issues.
   The order by property column will be resolved after import time
   (bug #580037).
 - The Store and Connection classes have block_access() and
   unblock_access() methods that can be used to block access to the
   database connection.  This can be used to ensure that an
   application doesn't access the database at unexpected times.
 - When using stores managed by ZStorm, a ZStormError will be raised
   on attempts to use a per-thread store from the wrong thread (bug
   #348815).
 - ResultSet.is_empty strips the ORDER BY clause, when present, to
   provide a performance boost for queries that would match a large
   number of rows (bug #246200).
 - A new ResultSet.get_select_expr method returns a Select
   expression built for a specified set of columns, based on the
   settings of the result set (bug #337494).
 - ResultSet.any and ReferenceSet.any strips the ORDER BY clause,
   when present, to provide a performance boost for queries that
   would match a large number of rows (bug #608825).
 - SQLObjectResultSet has a new is_empty method which should be used
   in preference to __nonzero__, because it is compatible with
   ResultSet.

Bug fixes:

 - SQLite reserved words are handled properly (bug #593633).
 - A bug in change checkpointing logic has been fixed to detect
   changes in mutable objects correctly and to prevent useless (or
   potentially harmful!) columns to be specified in updates (bug
   #553334).